1. Field of the Invention
This invention relates to compositions containing red Azo pigment salts. Specifically, the present invention relates to the compositions comprising the salts of C.I. Pigment Red 69 or C.I. Pigment Red 70 and a fortified latex.
2. Description of the Prior Art
Azo pigments have long been known in the graphic arts field. The use and preparation of azo pigments is well known in the art. These pigments are typically prepared by diazotizing various aromatic amino sulfonic acids and then coupling the intermediates with a compound such as Beta-naphthol or 2-hydroxy-3-naphthoic acid. The azo pigments are frequently laked with various bivalent metal salts to form cation--pigment salts having varied color characteristics.
U.S. Pat. No. 2,225,665 discloses manganese salts of red azo pigments for use in resinated coating compositions. These pigments are manufactured by coupling various aromatic amino sulfonic acids with Beta-hydroxy naphthoic acid. The pigment salts exhibited improved color retention.
High-hiding calcium color lakes having great full-shade brillance and improved light fastness are disclosed in U.S. Pat. No. 4,248,635. The azo pigment compositions disclosed in this patent have improved characteristics attributable to a predominant particle size less than 0.3 .mu.m.
New red dye pigments having improved tinctorial strength and fastness to light are disclosed in U.S. Pat. No. 3,545,992. These pigments are manufactured by coupling various O-amino benzenesulfonic acids with B-hydroxynaphthoic acid and reacting the pigments with combinations of metal salts to form multiple metal salt pigment complexes.
U.S. Pat. No. 4,190,578 discloses the azo coupling of pigment compounds in the presence of the precipitating metal salt so that coupling and precipitation take place simultaneously. This patent discloses the dialysis monitored preparation of metal salts of azo pigments.
There is, in addition, known art in the field dealing with various treatments of azo pigments and various compositions of azo pigments, resulting in pigment compositions with superior characteristics. U.S. Pat. No. 4,217,273, for example, discloses a process for preparing azo pigment compositions containing a modifier composition to improve the properties of the azo pigments. The modifier composition is prepared by chlorinating 2-hydroxy-3-naphthoic acid with a hypochlorite. The resulting compositions have increased color strength.
Colored latex and rubber products containing improved azo dyes are disclosed in U.S. Pat. No. 2,117,860. The brilliancy and light fastness of the colored rubber and latex products was improved. The azo dyes were made by coupling various diazotized aromatic amino sulfonic acids with 2-naphthol-3-carboxylic acid and laking with various metal salts. The rubber or latex compositions were made by physically milling the pigment lakes and rubber or latex between steel rolls.
U.S. Pat. No. 4,244,863 discloses a process for manufacturing azo pigment compositions with improved dispersibility. The pigment compositions are made by coagulating an aqueous azo pigment suspension in an aqueous latex of a polymer or polycondensate containing carboxyl groups, or an aqueous solution of a polymer or polycondensate containing carboxyl groups, by adding an electrolyte under thorough, intensive mixing.
A red Azo pigment commonly used in printing inks is C.I. Pigment Red 53 commonly known as Red Lake C. Red Lake C is a yellow-shade or "warm" red used in sheet-fed offset and web offset heat-set inks as well as letter press, gravure and flexographic inks. Red Lake C is made by diazotizing 2-chloro-5-aminotoluene-4-sulfonic acid (C-amine) and coupling this intermediate with Beta-naphthol. Red Lake C is typically laked with barium chloride to form the barium salt having the following formula: ##STR1##
The barium salt of Red Lake C is relatively inexpensive and demonstrates adequate color strength, satisfactory processing characteristics and satisfactory printing characteristics. It is known, however, that in water-based inks, Red Lake C has a strong tendency to "burn-out" when stored over time. "Burn-out" is defined as the tendency of a red pigment to lose its Red Value. For example, a water-based orange ink containing Red Lake C will gradually turn yellow.
There is one commonly known yellow shade red Azo pigment available for use in water-based printing inks which has good "burn-out" resistance: C.I. Pigment Orange 46, a commercial example of which is Clarion Red, manufactured by American Cyanamid Company. Clarion Red is believed to be made by diazotizing 2-amino-5-chloro-4-ethyl-benzene sulfonic acid and coupling the intermediate with Beta-naphthol. The resulting pigment is laked with barium chloride to form the barium salt, Barium Pigment Orange 46, having the following formula: ##STR2##
The Red Lake C and the Clarion Red molecules are nearly identical. The only difference is the presence of a methyl group in Red Lake C versus the presence of an ethyl group in Clarion Red. The "burn-out" resistance of Clarion Red is surprising.
Although Clarion Red has superior "burn-out" resistance to Red Lake C, Clarion Red is significantly more expensive.
Surprisingly, C.I. Pigment Red 70 and C.I. Pigment Red 69 have now been found to have good "burn-out" resistance, although the barium salts of both pigments tend to have very low color strength.
C.I. Pigment Red 70 is made by diazotizing the 6-amino-m-toluenesulfonic acid (4B Acid) and coupling the intermediate with Beta-naphthol. C.I. Pigment Red 70 is laked with barium chloride to form the barium salt, Barium Pigment Red 70, having the following formula: ##STR3##
C.I. Pigment Red 69 is made by diazotizing 6-amino-4-chloro-m-toluenesulfonic acid (2B Acid) and coupling the intermediate with Beta-naphthol. This pigment is laked with barium chloride to form the barium salt, Barium Pigment Red 69, having the following formula: ##STR4##
There has not been much commercial interest in either Barium Pigment Red 70 or Barium Pigment Red 69 (neither is registered in the T.S.C.A. inventory). This lack of interest probably comes from neither pigment salt having the color strength of Clarion Red or Red Lake C.
The inventor has studied the effect of various compounds on the color strength of the unexpectedly "burn-out" resistant Barium Pigment Red 69 and Barium Pigment Red 70 in order to obtain pigment compositions with "burn-out" resistance and color strength equal to or better than Clarion Red.